Lipolysis in Urfa cheese produced from raw and pasteurized goats’ and cows’ milk with mesophilic or thermophilic cultures during ripening

Lipolysis was evaluated in Urfa cheese made from raw and pasteurized goats’ and cows’ milk with mesophilic or thermophilic cultures. The acid degree values (ADVs) of the cows’ milk cheeses were significantly (P < 0.05) higher until 60 d of storage than that of cheese made from goats’ milk. Total free fatty acid (FFA) contents of goats’ milk cheese were significantly (P < 0.001) lower than that of cows’ milk cheese throughout ripening, whereas goats’ milk cheese flavour was higher (P < 0.05) than cows’ milk cheese. Pasteurization of milk prior to cheese-making has a negative influence, not only on the level of lipolysis throughout ripening, but also on the relative amounts of short chain FFAs and sensory properties of the cheeses (P < 0.001). Cheese produced without starter bacteria underwent significantly (P < 0.05) higher lipolysis than cheeses produced with mesophilic or thermophilic starter bacteria, while cheese made with thermophilic starter culture had similar flavour to cheese made without starter culture.     

Evolution of free amino acids during ripening of Caciocavallo cheeses made with different milks

The evolution of free amino acids (FAA) in Caciocavallo cheeses, made with cow milk (CC) and cow milk mixed with ewe (CE) and goat (CG) milk, was studied throughout ripening. In all Caciocavallo cheeses produced, the total free amino acid (TFAA) content increased during ripening. In general, the highest TFAA content was found in cow cheeses, and the lowest in CG cheeses, whereas CE cheeses ranged over an intermediate level. In all the analyzed samples, during ripening, the content of the individual FAA increased with the exception of arginine. Tyrosine and histidine were found only in CE samples from the middle to the end of ripening. The major FAA found throughout the whole ripening period, in all types of cheese, were leucine, phenylalanine, lysine, valine, asparagine, γ-aminobutyric acid, and ornithine. The TFAA and several AA showed significant differences in ripening time, whereas tyrosine and histidine showed significant differences in kinds of milk.     

Changes of composition and free fatty acid contents of Urfa cheeses (a white-brined Turkish cheese) during ripening: Effects of heat treatments and starter cultures

The influences of heat treatments (at 65 °C for 20 min or 72 °C for 5 min) applied to the milk and addition of mesophilic or thermophilic starter cultures, prior to cheese-making, on the composition and free fatty acid contents of Urfa cheeses were evaluated throughout the ripening period. Sensory evaluation of cheese samples was also performed on 90th day. The basic composition of ripened cheese samples was not significantly affected by the heat treatments and starter cultures. Heat treatments adversely affected the lipolysis and sensory properties of Urfa cheeses, particularly at 72 °C. The FFA contents of cheeses made from mesophilic and thermophilic cultures were similar. Cheese made from raw milk had a higher level of lipolysis than the cheeses made from milk inoculated with mesophilic or thermophilic lactic starters (p < 0.05).     

Free amino acid content of goat's milk cheese made with animal rennet and plant coagulant

BACKGROUND: Enzymes present in the flowers of Cynara cardunculus (cyprosins) are used in the production of some traditional Spanish and Portuguese cheeses, replacing animal rennet. The aim of this work was to study the changes that take place in free amino acids during the ripening of a goat's milk cheese (Murcia al Vino) manufactured with plant coagulant (PC) or animal rennet (AR). RESULTS: The total free amino acid (TFAA) concentration increased during ripening, with Ile, Val, Ala, Phe, Gaba, Arg and Lys representing more than 50% of the TFAA content at 60 days in both types of cheese. The TFAA concentration was significantly higher in cheeses made with PC (854 mg 100 g^?1 total solids (TS)) than those made with AR (735 mg 100 g^?1 TS). The concentration of most free amino acids, especially His, Ser, Gln, Thr, Ala, Met and Ile, was higher in the PC cheese. CONCLUSION: Cheese made using PC as coagulant presented higher contents of free amino acid throughout the ripening period than cheese made using AR. Therefore we can conclude that the use of PC to produce Murcia al Vino goat's cheese would accelerate the ripening process as a result of increased cyprosin proteolytic activity. Copyright © 2011 Society of Chemical Industry     

DETERMINATION OF pH CHANGE KINETICS DURING DIFFERENT STAGES OF KASHAR CHEESE MANUFACTURING FROM RAW AND PASTEURIZED MILK WITH ADDITION OF THERMOPHILIC, MESOPHILIC AND MIXED THERMOPHILIC CULTURE

The pH change kinetics during Kashar cheese production from raw and pasteurized milk with addition of thermophilic, mesophilic and mixed thermophilic-mesophilic lactic acid bacteria were evaluated. The kinetics of pH change were determined during milk ripening, cooking/holding and pressing/fermentation phases of Kashar cheese. The pH decreased logarithmically, nonlinearly, with time in the milk ripening period, and reduced linearly with time in the cooking/holding and pressing/fermentation stages. Pasteurization of milk retarded the rate of change in pH during the three periods. The highest rate of pH change was determined in the addition of thermophilic culture, followed by mixed thermophilic-mesophilic and then mesophilic ones during milk ripening. The pH change characteristics of cheese made with thermophilic starter were similar to the cheese made with mixed thermophilic-mesophilic culture, but different from mesophilic lactic acid bacteria during cooking/holding and pressing/fermentation stages.

PRACTICAL APPLICATIONS

One of the important factors in the control of cheese quality is the extent of acid production in the vat. Acid development at a desired rate is important during cheese making. The progress of acidification is monitored by pH change in the industrial Kashar cheese production. Three main stages have been recognized with respect to pH change: milk ripening, cooking/holding and pressing/fermentation. This study evaluated and compared the pH change kinetics during various stages of Kashar cheese making using raw, pasteurized milk with the addition of thermophilic, mesophilic and mixed thermophilic culture. This work may help in the comparison of raw and pasteurized milk, and in the selection of appropriate starter culture for Kashar cheese production.     

Indigenous raw milk microbiota influences the bacterial development in traditional cheese from an alpine natural park

Nostrano di Primiero is a 6-month ripened cheese produced from raw milk collected in the Paneveggio-Pale di San Martino Natural Park area in the Italian Dolomites. In summer, this cheese is made using milk collected from two different areas, Passo Rolle and Vanoi, in the Paneveggio Natural Park. During the experiment, the milk from the two areas was separately processed, and cheeses were made in the same cheese factory using the same technological process. The microbiota of raw milk and cheeses of the two areas was isolated and the dominant population was monitored by RAPD analysis and identified by 16S rRNA sequence. The milk of the Passo Rolle area was mainly composed of mesophilic strains, thermophilic Streptococcus thermophilus, and low amounts of enterococci were also found; the milk of the Vanoi area was dominated by mesophilic microbiota mostly Lactococcus lactis ssp. cremoris and ssp. lactis and Lactobacillus paracasei ssp. paracasei. The plating of the natural starter culture revealed the presence of a relevant community of thermophilic cocci and lower amounts of enterococci. The dynamic population analysis showed the importance of the natural starter culture in the first 2 days of cheese ripening in both cheeses. Moreover, the large biodiversity observed in the raw milks was also detected in the cheeses during ripening. The Vanoi cheese was dominated by Enterococcus faecium and Streptococcus macedonicus in the first two days and mesophilic 21 Lb. paracasei ssp. paracasei became the most represented population after 15 days of ripening. In the first few days, the Rolle cheese was characterized by being mainly composed of thermophilic S. macedonicus and S. thermophilus and secondarily by mesophilic cocci. During ripening, the microbiota composition changed, and at 15 days, mesophilic lactobacilli were the dominant population, but later, this was mainly composed of mesophilic cocci and lactobacilli. The taxonomical identification by 16S rRNA sequence confirmed a large biodiversity related to raw milk microbiota and only five strains of S. macedonicus, Lactobacillus plantarum, 21 Lb. paracasei ssp. paracasei, Lactobacillus fermentum and E. faecium were detected in both cheeses.     

Proteolysis and formation of volatile compounds in cheese manufactured with a bacteriocin-producing adjunct culture

Hispánico cheese, a semi-hard Spanish variety, was manufactured from a mixture of pasteurized cows' and ewes' milks (4:1) using a commercial mesophilic LD-type starter comprising Lactococcus lactis subsp. cremoris, Lc. lactis subsp. lactis, Lc. lactis subsp. lactis var diacetylactis and Leuconostoc mesenteroides subsp. cremoris. Varying amounts (0-1.0 g/kg) of an Enterococcus faecalis INIA 4 culture in milk were added as a bacteriocin-producing adjunct. Differences in pH between cheeses manufactured with and without the bacteriocin producer did not exceed 0.11 pH units. Starter lactococci lost viability more rapidly in cheeses made with the bacteriocin producer, which reached counts of up to 6 x 10(7) cfu/g during ripening. Aminopeptidase activity in 1-d-old cheese made from milk inoculated with 1.0 g bacteriocin-producing culture/kg was twice that in control cheese. Degrees of overall proteolysis and levels of total free amino acids in 45-d-old cheese made with 1.0 g bacteriocin-producing culture/kg were 1.80-fold and 2.17-fold those in control cheese of the same age. Inoculating milk with 1.0 g/kg bacteriocin-producing culture reduced the level of hydrophobic peptides in the resultant cheese, increased the concentrations of 3-methyl-1-butanal, diacetyl and acetoin, and resulted in the highest scores for flavour quality and flavour intensity throughout ripening.     

Effect of mesophilic lactobacilli and enterococci adjunct cultures on the final characteristics of a microfiltered milk Swiss-type cheese

The effect of four associations of adjunct cultures composed of mesophilic lactobacilli and enterococci, either solely or combined, on the microbiological, biochemical and sensory characteristics of Swiss-type cheese made using microfiltered cows’ milk and supplemented with propionibacteria was studied. The global pattern of growth was similar to that generally observed in raw milk cheese and interactions between microflora were highlighted during ripening. Enterococci, which negatively affected the survival of streptococci starters, seemed to play a limited role in the formation of volatile compounds, probably due to their low levels throughout ripening. On the contrary, mesophilic lactobacilli, which affected the evolution of propionibacteria, enterococci and L. delbrueckii subsp. lactis starter counts, modified free amino acid content, production of volatile compounds and organoleptic properties of mature cheese. This population appeared to be of major importance in the formation of cheese flavor as it was positively related to numerous potential flavor compounds such as alcohols and their corresponding esters, acetaldehyde and 4-methyl-4-heptanone. The original mesophilic lactobacilli present in milk could play an important role in the sensorial diversity of raw milk Swiss-type cheeses such as Comte.     

Texture and flavour development in Ras cheese made from raw and pasteurised milk

Texture, proteolysis and flavour development in Ras cheeses made from raw or pasteurised milk with two different thermophilic lactic cultures were monitored during ripening. Results showed that at day 1 of manufacture, the moisture content and pH were lower in raw milk cheese than in pasteurised milk cheeses. Levels of water-soluble nitrogen, casein breakdown, free amino groups and free fatty acids were higher in cheese made from raw milk than in that made from pasteurised milk. Textural characteristics, such as hardness, cohesiveness and chewines, increased in all treatments during the first 60 days of ripening due to the reduction in the moisture level during the second stage of salting (dry salting during the first 60 days of ripening). Cheese made from raw milk received the highest texture and flavour scores by panellists.     

Comparison of the characteristics of teleme cheese made from ewe's, goat's and cow's milk or a mixture of ewe's and goat's milk

Teleme cheeses were manufactured from ewe's, goat's and cow's milk and mixture of ewe's and goat's milk. Physicochemical and biochemical analyses of the cheeses at various stages of ripening and storage were performed. Cheeses made from goat's milk had lower moisture content than those made from other milks. No significant differences in the mean values of protein, salt and water activity (a _w ) of the different cheeses at all ages studied were found. Cheeses from goat's and cow's milk had higher contents of fat and fat in dry matter (FDM) compared to that of cheeses from ewe's milk and mixed milk. Significant differences were observed in the yield and yield on 56% moisture: cheeses from ewe's milk gave the highest yield and cheese from cow's milk the lowest. Significant differences were found in the ashes content of the different cheeses at all ages. No differences in cholesterol and cholesterol/fat contents of the four types of cheeses were found. Main and trace elements showed variability among the four cheeses.     

Effect of artisanal kid rennet paste on lipolysis in semi-hard goat cheese

This study examined the use of hygienised kid rennet pastes in model cheese systems and also in goat milk semi-hard cheeses to promote lipolysis. The results obtained indicated that the use of rennet paste caused greater lipolysis and increased, mostly, the short-chain free fatty acid (FFA) content. The model systems made with whole goat’s milk using rennet paste and commercial rennet mixture exhibited a higher FFA content than did the rennet paste-free controls (31,600 vs. 25,600 μmol/kg cheese). For the pilot cheeses made with bovine rennet and rennet paste mixture, the increase in FFA level after 45 days of ripening compared with the cheeses prepared only with commercial rennet was as much as 6600 (μmol/kg cheese) and the increase in the butyric acid content was also 1650 (μmol/kg cheese). Moreover, after 15 days of ripening, industrially prepared cheeses made with rennet paste exhibited greater levels of FFA than did the cheeses made with commercial rennet (11,500 μmol/kg at 45 days of ripening). Their flavour was stronger and the organoleptic characteristics were better accepted, which implies less ripening time for commercial cheese manufacture.     

Proteolysis, volatile compounds, and sensory evaluation in Hispánico cheese manufactured with the addition of a thermophilic adjunct culture, nisin, and calcium alginate-nisin microparticles

Nisin, free or incorporated in calcium alginate microparticles, was added to pasteurized milk (80% cows' and 20% ewes' milk) used for the manufacture of Hispánico cheese with a mesophilic starter and a thermophilic adjunct culture of high aminopeptidase activity. Addition of nisin incorporated in microparticles promoted early lysis of thermophilic adjunct culture bacteria. Extracellular aminopeptidase activity in 1-d-old cheese made with both thermophilic adjunct culture and nisin incorporated in microparticles was 1.8-fold higher than in cheese made with thermophilic adjunct culture and free nisin and 2.0-fold higher than in cheese made only with thermophilic adjunct culture without any addition of nisin. Addition of nisin, free or incorporated in microparticles, did not influence cheese proteolysis measured using hydrophilic or hydrophobic peptides, o-phthaldialdehyde ripening index, or free amino acids. Moreover, a total of 37 volatile compounds were identified in the volatile fraction of Hispánico cheese, using a dynamic headspace technique with a purge and trap system followed by a gas chromatography mass spectrometry analysis. The volatile compound profile was not influenced by nisin addition, either free or incorporated in microparticles, but addition of thermophilic adjunct culture enhanced the formation of 2-butanone, diacetyl, 2,3-pentanedione and acetoin and improved the flavor quality (sensory panel) of cheese.     

Proteolysis during ripening of Manchego cheese made from raw or pasteurized ewes' milk. Seasonal variation

Changes in nitrogen compounds during ripening of 40 batches of Manchego cheese made from raw milk (24 batches) or pasteurized milk (16 batches) at five different dairies throughout the year were investigated. After ripening for six months, degradation of p-kappa- and beta-caseins was more intense in raw milk cheese and degradation of alpha(s2)-casein in pasteurized milk cheese. Milk pasteurization had no significant effect on breakdown of alpha(s1)-casein. Hydrophobic peptide content did not differ between raw and pasteurized milk cheese, whereas hydrophilic peptide content was higher in raw milk cheese. There were no significant differences between seasons for residual caseins, but hydrophobic peptides were at a higher level in cheese made in autumn and winter and hydrophilic peptides in cheese made in winter and spring. Raw milk cheese had a higher content of total free amino acids and of most individual free amino acids than pasteurized milk cheese. The relative percentages of the individual free amino acids were significantly different for raw milk and pasteurized milk cheeses. The relative percentages of Lys and lie increased, while those of Val, Leu and Phe decreased during ripening. There were also seasonal variations within the relative percentages of free amino acids. In raw milk cheeses, Asp and Cys were relatively more abundant in those made in autumn, Glu and Arg in cheeses made in winter, and Lys and Ile in cheeses made in spring and summer. Biogenic amines were detected only in raw milk cheese, with the highest levels of histamine, tryptamine and tyramine in cheeses made in spring, winter and spring, respectively.     

发酵剂对牦牛乳硬质干酪蛋白降解和苦味关系的影响

用甘肃天祝新鲜牦牛乳为原料分别添加嗜温、嗜热和混合发酵剂制作硬质干酪,以pH 4.6-可溶性氮（soluble nitrogen,SN）、12%三氯乙酸氮（trichloroacrtic acid-N,TCA-N）、游离氨基酸（free amino acid,FAA）含量和疏水性肽/亲水性肽（S/Q）为蛋白水解度指标,研究3 种牦牛乳硬质干酪在6 个月内成熟过程中苦味和蛋白质降解之间的关系。结果表明：3 种干酪在成熟过程中pH 4.6-SN、12% TCA-N和FAA含量均呈上升趋势,苦味值与pH 4.6-SN、12% TCA-N和FAA含量成正相关,相关系数分别为0.400、0.412和0.458。3 种干酪成熟过程中S/Q的变化趋势和程度不同,嗜温发酵剂干酪中S/Q呈现降低趋势;嗜热和混合发酵剂干酪中S/Q均呈现先降低后增大的趋势,但在这两种干酪中S/Q的变化程度不同,嗜热发酵剂干酪在1～3 个月S/Q略有降低,在3～6 个月S/Q快速增大,而混合发酵剂干酪正好相反。S/Q与苦味值成极显著正相关（r=0.895）,S/Q可很好地反映干酪中苦味的强弱。而干酪中苦味强弱与蛋白质降解强弱密切相关,对蛋白降解程度越大的发酵剂制作的干酪越容易产生苦味,其中,嗜热发酵剂对干酪蛋白降解程度最大,混合发酵剂次之,嗜温发酵剂最小。     

Changes in the free amino acid content during ripening of Idiazabal cheese: influence of starter and rennet type

The effect of starter and rennet type on free amino acid release during ripening of Idiazabal cheese was studied. Four batches of cheeses were manufactured depending on the rennet used, commercial calf rennet or artisanal lamb rennet, and the addition or not of starter culture. Cheese samples contained 24 individual free amino acids Leu, Glu, Val and Phe showing the highest contents during the ripening. The results indicated that the release of the free amino acids during ripening was strongly affected by starter added to the cheeses, and that this effect varied markedly with the rennet used for cheesemaking. Total amounts of free amino acids were higher for the cheeses made with commercial calf rennet than for those made with artisanal lamb rennet, regardless of starter addition. Likewise, the highest total free amino acid levels were found in the cheeses made with starter, regardless of the type of rennet used.     

Behavior of Escherichia coli O157:H7 during the manufacture and ripening of feta and telemes cheeses

Pasteurized whole ewe's and cow's milk was used in the manufacture of Feta end Telemes cheeses, respectively, according to standard procedures. In both cases, the milk had been inoculated with Escherichia coli O157:H7 at a concentration of ca. 5.1 log CFU/ml and with thermophilic or mesophilic starter cultures at a concentration of ca. 5.3 to 5.6 log CFU/ml. In the first 10 h of cheesemaking, the pathogen increased by 1.18 and 0.82 log CFU/g in Feta cheese and by 1.56 and 1.35 log CFU/ g in Telemes cheese for the trials with thermophilic and mesophilic starters, respectively. After 24 h of fermentation, a decrease in E. coli O157:H7 was observed for all trials. At that time, the pH was reduced to 4.81 to 5.10 for all trials. Fresh cheeses were salted and held at 16 degrees C for ripening until the pH was reduced to 4.60. Cheeses were then moved into storage at 4 degrees C to complete ripening. During ripening, the E. coli O157:H7 population decreased significantly (P < or = 0.001) and finally was not detectable in Feta cheese after 44 and 36 days and in Telemes cheese after 40 and 30 days for the trials with thermophilic and mesophilic starters, respectively. The estimated times required for one decimal reduction of the population of E. coli O157:H7 after the first day of processing were 9.71 and 9.26 days for Feta cheese and 9.09 and 7.69 days for Telemes cheese for the trials with thermophilic and mesophilic starters, respectively.     

The effects of starter culture on chemical composition, microbiological and sensory characteristics of Turkish Kaşar Cheese during ripening

Kaşar cheese samples were produced from raw milk and starter culture-added pasteurized milk. Chemical, microbiological and organoleptic properties of kaşar cheeses were analysed at certain times during the ripening periods (on the 1st, 7th, 15th, 30th, 60th, 90th days). Generally, chemical parameters were not affected by starter culture. The pH, ripening index, water-soluble nitrogen and non-protein nitrogen did not show significant differences between the cheese samples. The addition of starter affected the microbiological quality of the cheeses. Starter culture-added kaşar cheeses contained low levels of total aerobic mesophilic bacteria, moulds and yeasts, and coliforms, and achieved higher organoleptic scores than those of cheeses made from raw milk. The starter cultures contributed to acidity and microbial quality of the cheese.     

Proteolysis in goat cheese made from raw,pasteurized or pressure-treated milk

Primary and secondary proteolysis of goat cheese made from raw (RA), pasteurized (PA; 72 °C, 15 s) and pressure-treated milk (PR; 500 MPa, 15 min, 20 °C) were examined by capillary electrophoresis, nitrogen fractionation and HPLC peptide profiles. PA milk cheese showed a more important hydrolysis (P<0.05) of α_s1-casein than RA milk cheese at the first stages of ripening (15 days), while PR milk cheese had a level between those seen in PA and RA milk cheeses. Degradation of β-casein was more important (P<0.05) in PA and PR than in RA milk cheeses at 15 days of ripening. However, from thereon β-casein in PR and RA milk cheeses was hydrolyzed at essentially similar rates, but at lower rates (P<0.05) than in PA milk cheeses. Pressure treatment could induce proteolysis of β-casein in a way, which is different from that produced by heat treatment. There was an increase in 4.6-soluble nitrogen (WSN) and in trichloroacetic acid (TCASN) throughout ripening in cheeses, but higher contents (P<0.05) in PA and PR milk cheeses at the end of ripening were observed. PR milk cheeses contained considerably higher content (P<0.05) of free amino acids than RA or PA milk cheeses. In general, heat and pressure treatments had no significant effect on the levels of hydrophobic and hydrophilic peptides.     

Combined effects of concentrated thermophilic and mesophilic cultures and conditions of curd acidifications on the manufacture and quality of kasseri cheese

The effect offour process variables on the biological acidification of curd to be usedfor the manufacture of kasseri cheese was examined. The variables were (i) concentrated starter cultures: a thermophilic mixture of Streptococcus thermophilus and Lactobacillus delbrueckii subsp bulgar-icus compared with a blend of Lactococcus lactis subsp lactis, Lactococcus lactis subsp cremoris and Lactobacillus casei subsp casei, and (ii) acidification temperatures: 30 and 40° C for the thermophilic cultures and 20 and 30°C for the mesophiles. The use of concentrated starter cultures enabled the cheese to be made in one day as compared with three in the traditional system usually using raw milk and no culture. The mesophilic blend combined with a lower scalding temperature (35°C) gave a higher yield than the alternative culture, and the cheeses were higher in total solids, acidity andsalt; the same cheeses were also harder and less elastic. The use of mesophilic cultures and a low acidification temperature (20° C) is recommended.     

Microbiological changes throughout ripening of goat cheese made from raw,pasteurized and high-pressure-treated milk

The bacteriological quality during ripening of raw (RA), pasteurized (PA; 72°C, 15 s) and pressure-treated (PR; 500 MPa, 20°C, 15 min) goat milk assessed by enumeration of total bacteria, psychrotrophic bacteria, Enterobacteriaceae, lactobacilli, enterococci, Micrococcaceae and lactococci was evaluated. The high pressure treatment applied was as efficient as pasteurization in reducing the bacterial population of milk. Experimental cheeses were made from RA, PA and PR milks to study the microbial population during ripening. Lactobacilli and lactococci were the predominant microbiota present during ripening in all the cheeses. There were no differences in numbers of starter bacteria during ripening. However, lactobacilli counts for RA milk cheese were significantly higher than for PA and PR cheeses in all the ripening stages studied. Micrococcaceae and enterococci remained at a secondary level, and no differences were observed between cheeses at the end of ripening. On the other hand, the number of Enterobacteriaceae decreased during ripening, but faster in PR milk cheese than in PA and RA milk cheeses. The results of this study suggest that goat cheese made from PR milk had similar microbiological characteristics to PA milk cheeses.